I was able to make parent window disable. However making the pop-up always keep raised didn't work. Below code works even for frame tags. Just add id and class property to frame tag and it works well there too.
In parent window use:
<head>
<style>
.disableWin{
pointer-events: none;
}
</style>
<script type="text/javascript">
function openPopUp(url) {
disableParentWin();
var win = window.open(url);
win.focus();
checkPopUpClosed(win);
}
/*Function to detect pop up is closed and take action to enable parent window*/
function checkPopUpClosed(win) {
var timer = setInterval(function() {
if(win.closed) {
clearInterval(timer);
enableParentWin();
}
}, 1000);
}
/*Function to enable parent window*/
function enableParentWin() {
window.document.getElementById('mainDiv').class="";
}
/*Function to enable parent window*/
function disableParentWin() {
window.document.getElementById('mainDiv').class="disableWin";
}
</script>
</head>
<body>
<div id="mainDiv class="">
</div>
</body>